“…[27][28][29][30][31][32][33] Kaolin, due to its acidic nature, can be a suitable replacement for various homogeneous catalysts. Kaolin has been used as a solid catalyst in FCC additives, 27 fluid catalytic cracking catalysts, 28 alkylation, 29 the protection reaction of carbonyl compounds, 30 halogenation, 31 biodiesel production, 32 and esterification. 33 Many research groups have developed solvent free syntheses using different catalysts, [34][35][36][37][38][39] but they have some drawbacks such as poor yield, long reaction times, high temperature, microwave and ultrasonication conditions etc.…”